Odds has been a betting term since the late 16th century - perhaps before that, but the earliest example found by the OED's helpers was from Henry IV, Part 2.
Odds had started as a singular noun meaning "something odd" (in the way "news" means something new), odd itself being used of a number which hadn't a pair to match it, so odds went on to mean an inequality, hence a difference (as in "What odds does it make?"). In betting, therefore, - and the principle was the same in the 16th century - the odds are the difference between the bet laid and the possible return from it. By the end of that century odds also meant simply "chances" ("The odds are that..."). The Guardian was really only saying that the chances of an interest rate hike were increasing, but it was nice to feel that there was a bit of a gamble in it.